1. Field of the Invention
This invention relates to digital time displays that are useful for general purpose timekeeping, i.e., the timekeeping needs and practices of ordinary individuals carrying out their usual day-to-day activities.
2. Description of the Prior Art
Digital time displays have been available to consumers since the early 1970s, initially in the form of wrist watches, and then in a wider variety of products and implementations, for example, clocks, clock-radios, motor vehicle dashboard and boat cockpit clocks, audio and video recorders, other household articles and applicances, and many others. Typically these products have displayed the numerical value of each current hour, followed by a colon and values of incrementing minutes from zero to fifty nine during each hour, sometimes with similarly incrementing seconds during each minute. To this inventor's knowledge, all such products, with one exception, have incorporated operating buttons or bars that require manipulation in prescribed sequences in order to set and control the time displays. The overwhelming majority of consumers has considered such controls to be tedious, inconvenient, complicated and, in some extreme cases, beyond understanding.
The one exception has been in some motor vehicle digital clocks that have been operated by a stem control. For example, some Japanese-manufactured vehicles have dashboard digital clocks that are set by pushing on a stem to reset seconds to zero, turning the stem clockwise to advance minutes to a desired value, and turning the stem counterclockwise to advance hours to a desired value. Since seconds are not displayed by these clocks, the zeroing of such values is indicated by the displayed minutes resetting to double zero, which compels the operator to perform two separate resettings, first seconds and then minutes, an inconvenience and annoyance when there is only a need to reset seconds. Moreover, such a stem control does not distinguish different kinds of setting or operating functions by how it is used, since rotation of it in either direction causes the same type of effect, advancement of numerical values in the display.
More recently, other types of digital time displays have been described, for example, in U.S. Pat. Nos. 4,264,966; 4,271,497; 4,483,628 and copending application Ser. No. 734,979, now U.S. Pat. No. 4,627,737 the disclosures of which are incorporated herein by reference. Typically, these teach the display of hour digits at the center of a display field, minutes after a current hour to the right of such hours, minutes before a next hour to the left of such hours and, optionally, seconds below the hour digits, cycling either between zero and thirty during all minutes, or from zero to fifty nine and fifty nine to zero during elapsed and remaining minutes, respectively.
Prototype wrist watches have been manufactured incorporating the specific time display system disclosed in Ser. No. 734,979. In these prototypes, at least four separate buttons are used for setting and control purposes. One button is recessed in the case and operated exclusively to switch the time display between the setting mode, indicated by flashing seconds, and the normal time display mode, indicated by steady seconds. Another switches the day/date display to the current month in the normal time display, and selects a function for setting in the setting mode. Another is unused during the normal time display, and advances a selected function to accomplish setting in the setting mode. The fourth button lights the display for viewing in the dark in the normal time display mode and is unused in the setting mode.
Some models of these prototypes have a fifth button, also recessed, that is operated exclusively for switching the time display between an alarm setting mode and the normal time display. In this instance, the second and third buttons described above are also operated in the alarm setting mode to select and set a time for sounding an audible alarm. The same buttons are operated in the normal time display mode, in combination and singly, to activate and turn off the alarm at the selected alarm time.
Despite the availability of explicit operating and setting instructions, some users of these prototypes have complained about the difficulty and complexity of correctly carrying out the described button manipulations. As a matter of fact, this inventor believes that since their advent, all digital timepieces have been criticized more frequently because of the difficulty of setting and operating them than for any other reason, which has posed a major problem to their utility and salability. This is perhaps epitomized by one reader's letter to the editors of a news magazine, June 16, 1986 edition, which expressed the "joy" of using analog watches because they can be reset without having to carry the printed instructions in one's wallet.